BIO311 Connect: Mapping in Bacteria, Conjugation, Transformation (Ch. 7)

(a). Pilus (b). Conjugation bridge (c). Relaxosome (d). Relaxase (e). Exporter

(a). Contacts the recipient cell and draws the donor and recipient cell together (b). Passageway for DNA transfer between the donor and recipient cell (c). Protein complex that recognizes the origin of transfer (d). Enzyme that rejoins the ends of the transferred DNA to form a circular molecule (e). Complex of proteins that spans the membranes of the donor cell

(a). conjugation (b). transduction (c). transformation

(a). transfer of genetic material from a donor cell to a recipient cell through direct contact between the cells (b). transfer of genetic material from one bacterial cell to another by a virus (c). uptake of genetic material from the environment by a bacterial cell

What are the functions of the relaxosome in conjugation?

- It recognizes the origin of transfer in the F factor. - It separates the two strands of the F factor.

A certain bacterial strain is designated met+ leu- thr- thi+ . Which nutrients must be included in the growth medium in order for this strain to grow?

- Leucine (leu) - Threonine (thr)

Which of the following are examples of traits affected by allelic variation that are rapidly observable in bacteria?

- Nutrient requirements - Antibiotic sensitivity

Which of the following are mechanisms that bacteria use for genetic transfer?

- conjugation - transformation - transduction

If the genotype of a bacterial cell is leu+ , then the bacterial cell ____________ .

- is able to synthesize leucine - does not require leucine to be included in its growth medium

What is required in order for genetic material to be transferred between two bacterial cells by conjugation?

Physical contact between the two cells

A bacterial strain has the genotype met- leu- thr+ thi+. Which nutrients does this strain require in its growth medium?

Methionine (met) and leucine (leu)

How do F+ and F- strains of E.coli differ from one another?

Only F+ strains contain an F factor

Horizontal gene transfer is possible _____________ .

between members of the same species or members of different species

The passageway for DNA transfer between a donor cell and a recipient cell is called a conjugation ____________ .

bridge

A bacterial strain has the genotype met- . This means that the bacterial strain

cannot synthesize methionine, so methionine must be included in its growth medium

Any process in which one bacterium transfers genetic material to another bacterium is called ____________ .

genetic transfer

A bacterium is typically _____________ for a particular gene, meaning that it only has one copy of the gene.

haploid

For a given gene, a bacterial cell is usually ______________ .

haploid

During transformation, a functional gene may be replaced with a nonfunctional gene within the bacterial chromosome if the two copies of the gene align and exchange pieces through a process called ______________ _______________.

homologous ; recombination

In order for a segment of transformed DNA that carries a lys+ gene to be incorporated into a lys— cell _____________

homologous recombination must occur

The transfer of genetic material to an organism that is not the offspring of the donor organism is referred to as _______________ gene transfer.

horizontal

What is contained in a minimal medium?

only essential nutrients

In order to be replicated independently of the bacterial chromosome, a plasmid must have its own _____________ of ______________

origin ; replication

To initiate conjugation, the F factor must be cut at a site called the ___________ of ____________ .

origin ; transfer

During conjugation, the initial contact between the donor and recipient cell involves structures called sex __________ that are made by F+ strains.

pili

A bacterial strain that can synthesize a nutrient (e.g., methionine) and does not require that nutrient in its growth medium is called a(n) _______________ .

prototroph

During conjugation, the protein complex that recognizes the origin of transfer in the F factor, cuts one of the strands, and then separates the two DNA strands is called the ___________ .

relaxososome

Bernard Davis conducted experiments with a U-tube apparatus similar to the one in this figure. In his experiment, conjugation did not occur because _______________ .

the bacterial cells were too large to pass through the filter

A bacterial strain that cannot synthesize a particular nutrient and therefore requires that nutrient to be included in its growth medium is called a(n) _______________ .

auxotroph

Place the events that occur during conjugation in the correct order

1. Pili fro an F+ cell make contact with an F- cell. 2. A conjugation bridge from between the cells 3. The F factor DNA is cut 4. Single-stranded DNA and the relaxes protein form a nucleoprotein 5. The nucleoprotein passes through the exporter complex 6. Relaxase joins the ends of the donated DNA together to form a circular molecule

What is an episome?

A plasmid that can integrate into a chromosome

The three mechanisms that bacteria can use to transfer genetic material are _______________ , _____________ , and _______________ .

Conjugation ; Transduction ; Transformation

In addition to their circular chromosome, strain of E. coli that can acts as donors during conjugation contain a small circular segment of DNA called a(n) ________ factor

F

A strain of E. coli that contains an F factor and can act as a conjugation donor is designated _____________ , and a strain that lacks the F factor may be a recipient and is designated ____________ .

F+ ; F-

What is the significance of a plasmid's origin of replication?

It allows the plasmid to be copied separately from the bacterial chromosome

Why is genetic transfer advantageous to bacteria?

It increases genetic diversity

What DNA sequence in the F factor is recognized and cut to begin the process of conjugation?

The origin of transfer

What is genetic transfer?

The transfer of genetic material between bacterial cells

When a bacterial cell takes up foreign DNA from the environment, the processes is called ____________ . When a virus transfers DNA from one bacterial cell to another, it is called ____________ . Transfer of DNA between two living bacterial cells in direct contact with one another is called ________________ .

Transformation ; Transduction ; Conjugation

Which of the following statements about transformation is correct?

Transformation is a natural process that has evolved in some species of bacteria.

What is a plasmid?

a DNA molecule that can exist independently of the bacterial chromosome

What is a competent cell?

a bacterial cell that can take up foreign DNA

What is an auxotroph?

a bacterial strain that requires a certain nutrient to be supplemented in its growth medium

What is the F factor that is found in F+ donor strains of E. coli?

a small circular segment of DNA that is separate from the circular chromosome

Sensitivity to _______________ and nutrient requirements for growth are examples of easily discernible traits in bacteria.

antibiotic

F factors carry genes that are necessary for the process of ____________ .

conjugation

This figure shoes the results of an experiment in which two bacterial strains were mixed together before being plated on media lacking certain nutrients. The results of this experiment suggest that DNA was transferred between the two strains by _____________ .

conjugation

In Bernard Davis's experiment with a U-tube apparatus similar to the one shown here, bacteria could not pass through the filter, and conjugation did not occur. This experiment supported the conclusion that ____________ .

conjugation requires physical contact between two cells

Genetic transfer is advantageous to bacteria because it increases genetic _________________ .

diversity

A bacterial strain that is a leucine phototroph is a strain that ___________ .

does not require leucine in its growth medium

This figure demonstrates the growth of two bacterial strains individually or after they were mixed together. Based on the data in this figure, which genes were transferred from one strain to the other to allow growth on the agar plates?

met+ and bio+

A growth medium that contains only the essential nutrients required for the growth of a wild-type bacterial species is called a(n) _______________ medium.

minimal

Frederick Griffith is known for the discovery of __________ .

transformation